Ever wonder exactly who "the friend" is dishing the dirt on celebrities? Well, in the case of the Rielle Hunter-John Edwards scandal, we know exactly who it was: the memorably-named Pigeon O'Brien. And now, she's explaining why, exactly, she went to the Enquirer, broke their affair, and effectively ended his political career.

Pigeon O' Brien, a publicist and editor who tells her story in the HuffPo today, had known Rielle way back, when she was Lisa Druck and a notorious party-girl who was apparently known for "non-monogamy" and shouting personal information from within bathroom stalls. Quoth Pigeon, "There was something charming and feral in her aggressive bubbliness." "Friends," more than friends, we're getting. Later, after Rielle re-invented herself as the kooky guru we'd all come to know, they reconnected.

O'Brien became Rielle's confidant — sort of. It took a while for her to understand that Rielle's "John" was the same one running for President. When she did, she was appalled.

Rielle checked in often about her new love. This is madness, I thought, this is destined to fail. It was a looming train wreck. She continued to gush via email; he continued to show up on TV with his smiling wife. Guilt became my constant companion. Daily contemplation of this was gross. It was not something I believed in. How was I to reconcile Mr. Values and Miss Enlightenment with what was becoming a tawdry charade? A year and a half went by. Rielle was not experiencing her truth, she had her eye on the prize: a president.

She kind of blamed Elizabeth, though.

I knew that Elizabeth knew. Instead of reeling her husband in, smartening him up and zipping his pants, instead of getting him to respect the trust of every supporter and voter depending on him, she went, with homey interviews about her marriage, woman-to-woman at Rielle. Look out, I thought.

And then, there were the kids.

The three people who could not be fooled — by leak, headline, alibi or lie — were the Edwards children. They had a mom and a dad, and there was a new lady they had to deal with. My heart ached for them. They deserved as easy and trouble-free upbringing as any children do. Every day I felt I was complicit in ruining their home.

I get the burden of guilty knowledge, especially in the case of a hypocritical public figure. Hey, that would weigh on anyone. And I'm guessing Rielle wouldn't exactly be the easiest woman in the world to reason with, given the blithe self-justifying amorality she's displayed throughout. What's a little murkier is choosing to go the tab route — not that we imagine other, more respectable avenues are as willing to shell out (a question O'Brien doesn't address.) Well, here's O'Brien's rather lofty explanation:

This is the function of the press in a democracy: It is to present the truth so that we may cast our votes knowledgeably. We have absolutely no right to know who kisses whom in a darkened car or pokes someone on Facebook. But other personal choices tell us if this person is fit to govern. What is this person's essential character? What might this person do once given trust? Does this person respect women as human beings? Does he take responsibility for his actions? Does he betray those who trust in him behind their backs? We don't just have a right to know, we have a responsibility to know. Our constitutionally mandated free press serves this role.

More materially, she says other publications wouldn't take her calls.

But throughout it all, she says, she maintained her faith in Rielle. Well, until she did the unthinkable.

I tried to rally for Rielle. I'd assumed Rielle — now the mother of Edwards's child — was another innocent part of the widespread collateral damage, like his disappointed supporters. I'd believed in her and I'd sworn up and down she had not made a sex tape, that just a dirty rumor meant to smear her as a slut. I found out, after vouching for her character on national TV, that they had indeed filmed themselves having sex. I was crushed. While my gut twisted keeping her cloaked in her secret, they were making personal pornos.

So, she's okay with the year-long affair with the married dude with the sick wife and young kids, but draws the line at an amateur sex tape? That was the bridge too far? Well, it takes all kinds, as they say, to make a world.

O'Brien declares that she's "at peace" with her decisions, but writing this piece in the first place would seem to tell a different story. Hers was probably a difficult decision and had she not come forward, chances are the story would have come out eventually. But Woodward and Bernstein this was not. The whole situation was simply too tawdry for anyone to come out smelling like a rose.